1. Field of the Invention
The present invention relates to a hood isolator for motor vehicles.
2. Description of the Prior Art
Large motor vehicles, such as semitractors and trucks, have large, bulky and heavy hoods attached to their cabs. The hoods are typically fastened at the front of the chassis using a front hood hinge. In many designs, the bulky hood opens to a vertical position by pivoting on the front hood hinge. The front hood hinge must therefore support the weight of the heavy hood in the open position.
At the back of the hood, the hood mounts to the cab using brackets. The brackets preferably engage each other closely, allowing a minimal clearance or tight interface between the hood and cab brackets. This tight interface reduces annoying noises, such as squeaks, buzzes and rattles during movement between the hood and cab.
During movement, the front of the hood and the front hood hinge are under stress. Cab movement in the vertical or fore and aft directions stresses the hood. The tight interface between the hood and cab brackets increases the stress by transmitting energy from the cab to the large hood and the front hood hinge as the cab moves. Constant stress on the front hood and front hood hinge can increase metal fatigue and possibly lead to a dangerous failure of the hinge when the hood is opened.
One prior art method reduces the stress by strengthening or heavily reinforcing the hood. The extra weight increases the stiffness of the hood and helps dampen some of the stress during movement. Unfortunately, the heavier hood is more expensive to make and the extra weight increases the cost of running the truck by increasing fuel consumption.
This method also forces more stress into the front hood hinge. To reduce the hood hinge stress, the front pivot points are made from an elastomer. This method works but adds a lot of weight, cost and size to the hinge, which makes the front hood hinge more difficult to package and blocks more cooling air from the radiators.
Other methods isolate the noises and hood by mounting the hood to the frame rather than the cab. While this method isolates the hood, it does not hold the hood in relation to the cab. The hood, therefore, is tied to the frame and is more difficult to align to the cab during assembly.
Another method uses an arm 110 inserted within a bracket 112. (FIG. 1) Arm 112 attaches to the cab, while bracket 112 attaches to the hood. This method allows some isolation of the stress on the hood as the cab travels rearward. The apparatus, however, absorbs little energy transmitted from the cab to the hood. Rather, the isolator apparatus is a conduit for transmitting the energy to the bracket and subsequently down the hood to the front and the hood hinge.
This method also requires the arm to fit tightly within the bracket on the forward side. If the head is loose within the bracket, the head can bang against the bracket during motor vehicle movement. As the arm and bracket are usually metal or hard plastic, this banging increases the wear and tear of the head and bracket. Not only is stress from the cab still radiating to the front of the hood and front hood hinge, the bracket and arm themselves are under heavy stress as well.
An additional method loosely attaches the hood to the cab. This method allows little hood to cab alignment as well as frequent bangs and squeaks to occur.
Therefore, it is one object of the invention to reduce or isolate the stress on the hood from the cab during movement. Another object of the invention is to tightly hold the isolator arm within a bracket to prevent shifting or movement of the isolator arm within the bracket. Still another object of the invention is to reduce annoying noises, such as buzzes, squeaks and rattles. A further object of the invention is to produce an apparatus that is easy to assemble and align the hood to the cab.
According to the invention there is provided a hood isolator designed for a motor vehicle, especially a heavy truck. The hood isolator allows a minimal clearance between the hood mounting means and the cab mounting means while reducing the stress on the hood during cab movement, especially the stress on the front of the hood and front hood hinge. The hood isolator comprises a bracket with a mounting plate, a front plate and an intermediate plate therebetween. The three plates have first and second sides. A receptor cup with a wall and an opening at one end is located at least partially within the bracket. A connector extends from the receptor cup wall to the first side of the bracket.
An isolator arm has a head and a distal end opposite the head. The head fits at least partially within the receptor cup through the opening. The isolator arm mounts to the vehicle at the distal end, while the bracket preferably mounts to hood with the mounting plate.
Additional effects, features and advantages will be apparent in the written description that follows.